Prior art silicon-on-glass fabrication processes require bonding a silicon thin film to glass, while the device fabrication process is similar to that of SOI process, except the highest temperature is limited by the thermal stability of glass, which is generally 650° C. or less. At temperatures lower than 650° C., the implanted ions cannot thoroughly be activated.
Colace et al., Efficient high-speed near-infrared Ge photodetectors integrated on Si substrates, Applied Physics Letters, Vol. 76, No. 10, pp 1231–1233 (2000), describes a process whereby pure germanium may be grown directly on a silicon wafer and used in low-cost monolithic transceivers for optical communications applications.